Safety means for oven door latching mechanism



SAFETY MEANS FOR OVER DOOR LATCHING MECHANISM Original Filed Aug. 4,1964 R. B. BARBER Aug. 25, 1970 2 Sheets-Sheet 1 aa a R NA we W. 5 w M Oa PIC-5.2.

MJQZ ZA HlS ATTORNEY R. B. BARBER Re. 26,943

swan mums won ovsn noon LATCHING MECHANISM 2 Sheets-Sheet 2 OriginalFiled Aug. L, 1964 MM/K424;

H- 5 ATTORNEY United States Patent 26,943 SAFETY MEANS FOR OVEN DOORLATCHING MECHANISM Ronald B. Barber, Cheshire, Conn., assignor toGeneral Electric Company, a corporation of New York Original No.3,313,918, dated Apr. 11, 1967, Ser. No. 387,439, Aug. 4, 1964.Application for reissue Sept. 8, 1969, Ser. No. 871,808

Int. Cl. F27d 11/02 US. Cl. 219-413 17 Claims Matter enclosed in heavybrackets appears in the original patent but forms no part of thisreissue specification; matter printed in italics indicates the additionsmade by reissue.

ABSTRACT OF THE DISCLOSURE A high temperature oven for domestic usecomprising a cabinet structure enclosing a box-like oven liner that hasan open front provided with an access door that cooperates with the ovenliner to define an oven cooking cavity, electrical heating means forsupplying heat energy into the oven cavity for normal cooking operationsbetween about 150 F. and 550 F. as well as for a heat cleaning operationbetween about 750 F. and 950 F. for removing food soil lodged on thewalls of the oven liner, and door latching means movable between openand closed positions for holding the door closed during the heatcleaning operation. The door latching means having a safety means toinsure that the door may not be unlatched when the oven is operating ina high temperature range above normal cooking temperatures.

The present invention relates to a latching means for the door of abaking oven, and particularly to a safety means to insure that the doormay not be unlatched when the oven is operating in a high temperaturerange above normal cooking temperatures.

This invention is an outgrowth of the development of a self-cleaningoven as is taught in the recent patent of Bohdan Hurko, No. 3,121,158,which issued on February 11, 1964, and is assigned to the GeneralElectric Company, the assignee of the present invention. Such aselfcleaning oven would have the normal cooking functions of baking andbroiling within a temperature range between about 150 F. and 550 F., aswell as a heat cleaning operation where the temperature is raised to amaximum somewhere between about 750 F. and 950 F. for removing the foodsoil and grease spatter and accumulates on the walls of the oven linerduring normal usage. Such a reaction may be characterized by the termpyrolysis which means the chemical decomposition of matter by theapplication of heat.

Undoubtedly, the major annoyance in using an oven for cooking is thedifficulty encountered in keeping the walls of the oven liner cleanafter repeated usage. It is unavoidable that food particles and greasespatterings will accumulate and discolor on the hot oven surfaces duringnormal cooking operations. Strong chemical cleaning agents have beendevised and are commercially available for the express purpose ofremoving food soil of this type under these conditions. However, eventhe best of these cleaning agents require a strong rubbing action, and agreat deal of time and effort is needed to complete the tasksatisfactorily. Also, there is a safety hazard that the chemicals mightcause injury to the users hands or eyes if the directions for use arenot followed closely.

Once the principle of pyrolysis was perfected for automatic ovencleaning, many different systems of applying the heat and controllingthe cleaning operation were devised to obtain the desired results. Togain the maximum reliability, standard components were used wherepossible to take advantage of years of engineering development andknow-how gained by working with the components, and they were arrangedin fail-safe combination so that after years of trouble-free usage ofthe oven any failure of a component would not constitute a safetyhazard. Instead, the failure of these components would renderinoperative the heating circuit or function in which the componentoperates.

In such a high temperature oven, it is of primary impoitance to latchthe oven door before the cleaning cycle is set in motion, and to insurethat the door cannot be opened during the cycle so that only a measuredamount of air enters the oven cavity during the pyrolytic process.

The principal object of the present invention is to provide a hightemperature baking oven having a door latching means with an automaticlocking means that locks the door latching means in its closed position,there being positive release means provided for the automatic lockingmeans where the release means can only be operated after the completionof the heat cleaning cycle.

A further object of the present invention is to provide a door latchingmeans of the class described with a first interlock switch means toinsure that the door latching means is in its closed position before thehigh temperature cycle can be initiated, and a second interlock switchmeans to insure that the automatic locking means is in its closedposition before the high temperature cleaning cycle can be initiated,where the safety controls for the oven are remotely located adjacent therear of the oven in a relatively cool area.

A still further object of the present invention is to provide a doorlatching means of the class described with a spring biased locking meansoperative when the door latching means reaches its closed position oralternatively reaches either its open or its closed position, with theaddition of an electrically responsive means for overcoming the springbiasing member only after the completion of a heat cleaning cycle.

The present invention, in accordance with one form thereof, is embodiedin a heated cavity or cooking apparatus comprising walls defining anoven cavity where one wall of the cavity includes a door for gainingaccess thereto. A heating means either electric or gas is supplied forthe oven and means is furnished to control the heating means for bothnormal cooking operations having a temperature range between about F.and 550 F. as well as for a high temperature heat cleaning cycle wherethe maximum temperature reaches somewhere between about 750 F. and 950F. A door latching means is movable between an open and a closedposition, and it is adapted to seal the oven door when the temperaturesare to be raised above the normal cooking temperatures. Associated withthe door latching means is an automatic locking means that engages thedoor latching means in the closed position and prevents the manualoperation of the door latching means. A release means is connected tothe automatic locking means for overcoming the automatic locking meansand freeing the door latching means for manual operation. The releasemeans is controlled in such a way that it can only be operated after thecompletion of the heat cleaning cycle so as to insure that entry cannotbe gained to the oven cavity when the oven temperatures are above thenormal cooking temperatures. Other modifications include a firstinterlock switch means formed as part of the control means for the heatcleaning cycle so as to be closed only when the door latching means isin its closed position. Another modification is to incorporate a secondinterlock switch means in the control means for the heat cleaning cyclewhich is closed only when the automatic locking means is in its closedposition before it is possible to energize the heat cleaning cycle.Further improvements incorporate the location of the two interlockswitch means as well as the release means for the automatic lockingmeans toward the back of the oven in arelatively cool area so that hightemperature conditions do not adversely affect the operation thereof.

Two later versions of the present invention are incorporated in thedesigns of (1) an [earlier filed copending] application, Ser. No.323,809 of Clarence Getman entitled Oven Door Latching System, now Pat.No. 3,350,542 and (2) an [earlier filed copending] application, Ser, No.323,810 of Samuel C. Jordan entitled Circuitry for Electric Oven" nowPat. No. 3,270,183, both of which applications were filed on Nov. 14,1963, and are assigned to the assignee of the present invention. Theaforesaid German and Jordan applications were earlier filed copt'mlingapplications with respect to the application on which my original Pat.No. 3,313,918 was issued, namely application Scr. No. 387,439 filed Aug.4, 1964.

My invention will be better understood from the following descriptiontaken in conjunction with the accompanying drawings and its scope willbe pointed out in the appended claims.

FIGURE 1 is a right side elevational view of a free standing electricrange embodying the present invention with parts broken away to show theoven cavity;

FIGURE 2 is a fragmentary plan view showing the oven door latchingmechanism in an open position, taken on the line 2-2 of FIGURE 1;

FIGURE 3 is a fragmentary cross-sectional elevational view taken at theback of the oven on the line 3--3 of FIGURE 2, but with the oven doorlatching mechanism moved to a closed position, and showing the automaticlocking means for the door latching mechanism as well as a solenoid typerelease means;

FIGURE 4 is a schematic diagram of the power and control circuits forthe oven of the present invention.

Turning now to a consideration of the drawings and in particular toFIGURE 1. there is shown for illustrative purposes a free-standingelectric range having a top cooking surface or cooktop 11 with aplurality of surface heating elements 12. an oven cavity 13 formed by abox-like oven liner 14 and a front-opening drop door 15. The oven cavityis supplied with two standard electric resistance heating elements,namely, a lower baking element 16 and an upper broiling element 17. Athird heating element has been added adjacent the oven door 15. and itis a mullion or perimeter heater 18 that is wrapped around the ovenliner in a manner that is taught by I. K. Newell. Jr.. in his Patent3,017,488 which is assigned to General Electric Company, the assignee ofthe present invention. The control of the surface heating elements 12 isobtained by selector switches (not shown) that are located in a controlpanel 20 formed in a backsplash 21 adjacent the back edge of the cooktop11. This control panel also includes the control means for the variouscircuit combinations of the oven as well as temperature controlthermostat and clocktimer devices as is old and well known in this art.

Other structural features that might be mentioned by name would be theouter range body or cabinet 23 which has an appearance finish on theouter surface and which supports and encloses the various components ofthe range. Sandwiched between the oven liner 14 and the range body is athick blanket of thermal insulating material 24 such as fiber glass orthe like. The amount of insulation being used has been increased overthe ordinary amount of insulation used for standard ovens because of thehigh operating temperatures encountered during the heat cleaningoperation which will reach a maximum oven air temperature somewherebetween about 750 F. and about 950 F. Another component shown is an aircirculating fan 26 located in the bottom portion of the range adjacentthe back wall thereof and supported in an opening in an insulation guardpanel 43. This fan serves to draw relatively cool room air into therange body 23 through the back of the backsplashcr 21 and down avertical air duct or wiring channel 27 at the back of the oven and intothe bottom portion of the range that include; space for a pull-outdrawer 28 for the storage of cooking utensils and the like. From thisarea the air rises up suitable ducts (not shown) built into the oppositeside walls of the oven where the air is discharged under the cooktop 11and is exhausted through openings in and around the surface heatingelements 12.

It has been found desirable to provide a latch means for the oven door15 to insure that this door is closed and cannot be opened while theoven is being operated on the high temperature heat cleaning cycle. Theparticular door latch mechanism is identified as element 30 in FIGURE 1and it is located in the area between the cooktop 11 and the top wall ofthe oven liner 14 adjacent the oven door. Only brief mention will bemade of the exact nature of the door latching mechanism since it doesnot form part of the present invention but is disclosed and claimed inthe copending application of Clarence Getman, Serial No. 277,174 whichwas filed on May 1, 1963, and issued June 15, 1965 as Patent 3,189,375and is assigned to General Electric Company, the assignee of the presentinvention. The latch mechanism 30 includes a manually operable handlelever 31 which extends through an elongated slot in the front edge ofthe cooktop 11 in a position that parallels the top edge of the ovendoor 15. Referring to FIGURE 2, the handle lever 31 is pivotallysupported about a vertical pivotal axis 32 from a stationary mountingbracket 33 that is fastened to the inner surface of the front of thecooktop 11. The handle lever 31 is shown in FIGURE 2 in is open positionand it is adapted to swing through an angle of about 60 in moving to itsclosed position. The handle lever 31 operates a pivoted latching bolt 35which is joined by a pin and slot, lost motion connection (not shown)which serves to swing the latching bolt 35 out of the range body andinto engagement with a slotted keeper portion (not shown) formed on theinner surface of the oven door 15. Notice that the latching bolt 35 isrecessed within the range body when the handle lever is in its openposition as shown in FIGURE 2. Moreover, the latching bolt 35 extendsgenerally perpendicularly to the front wall of the cooktop 11 when theoven door is in its fully locked position.

The description given above has been for the purpose of setting thestage and explaining the environment in which the present inventionfunctions. Associated with the door latching mechanism 30 is anautomatic locking means generally identified as element 38 which islocated at the rear of the oven and serves to lock the door latchingmcchanisrn 30 in both the open and closed positions of the mechanisms.The purpose of locking the door latching mechanism 30 in its openposition is to insure that the handle lever cannot be thrown to theclosed position inadvertently or by the tampering of a child. Thelatching mechanism is locked in the closed position to insure that theoven door 15 cannot be unlocked and the door opened during any part ofthe high temperature heat cleaning cycle.

Associated with the handle lever 31 and the automatic locking means 38is a movable rod 39 that is pivotally connected at one end to the handlelever as by the pivot pin 40 and it extends rearwardly to the back ofthe oven as is best seen by comparing FIGURES 2 and 3. The reason forthe movable rod 39 is to locate the automatic locking means 38 for thedoor latching mechanism 30 in a relatively cool area within the verticalair duct 27 so that several interlock switches 63 and 65 cooperatingtherewith will not be adversely affected by high temperatures. Forpurposes of support, a rigid upturned channel member or support bracket42 parallels the movable rod 39 and is fixed at one end to thestationary mounting bracket 33 of the door latching mechanism and isfixed at its opposite end to an insulation guard 43 as by the fasteningmeans 41 shown in FIGURE 2. Accordingly, as the handle lever 31 isshifted between its open to its closed positions, the movable rod 39will reciprocate within the support bracket 42 through a short distance.

Now looking at FIGURE 3, the automatic locking means 38 for the doorlatching mechanism 30 is illustrated as a lever 44 that is pivotallyconnected at one end as at 45 to a vertical side flange of the supportbracket 42. The opposite end of the lever 44 is supported on acompression spring member 46 which is seated on a fixed bracket 47. Aspring retaining member 47 is in the form of a bolt 48 that extendsthrough the center of the spring and is pivotally connected to the lever44 as at 49. The lower end of this bolt 48 extends through an enlargedopening 50 in the bracket 47 and is pivotally connected as at 52 to aplunger 53 of a solenoid 54. The solenoid is available as a releasemeans of the automatic locking means 38 to overcome the lifting force ofthe spring 46 as will be better understood hereinafter.

As is best seen in FIGURE 3, the rearmost end of the movable rod 39 isprovided with a pair of spaced detents 56 and 57 that are joined by ahorizontal slot 58. These detents and slot are formed in a verticalflange 59 of the movable rod 39 for cooperation with a horizontal pin 60formed on the adjacent side of the lever 44. Thus, in order to move thehandle lever 31 or" the door latching mechanism 30, it is firstnecessary to depress the lever 44 so as to drop the pin 60 out of one ofthe detents 56 and 57 and into the horizontal slot 58. This unlocks thedoor latching mechanism for freedom of movement between its open andclosed positions. This spring member 46 normally biases the level 44 inan upward direction so that once the handle lever 31 reaches one of itsextreme positions the spring 46 will tend to raise the lever 44 therebypositioning the locking pin 60 within one of the detents 56 or 57. Thus,the lever 44 and spring 46 serve as an automatic locking means 38 of thedoor latching mechanism 30.

Admittedly, an actuator or release means must be provided for loweringthe lever 44 and unlocking the door latching mechanism. Such a releasemeans is exemplified by the solenoid 54 which was mentioned earlier asbeing connected to the lever 44 through the plunger 53 and bolt 48. Whenthe solenoid 54 is energized, the plunger is drawn downwardly therebydropping the pin 60 out of one of the detents 56 or 57. Thus, when thesolenoid is de-energized the lever 44 is free to move automatically intolocking engagement with the door latching mechanism under the biasingforce of the spring. Accordingly, a definite motion or force isnecessary in order to unlock the door latching mechanism. Hence, themechanism cannot be thrown inadvertently to either its open or closedpositions.

Two interlock switch members are combined with the door latchingmechanism 30 and the automatic locking means 38 at the back of the oven.The first interlock switch is a single pole, single throw latch switch63 that is held open during normal cooking operations by the position ofthe rod 39 as is seen in FIGURE 2, and the switch is adapted to beclosed when the door latching mechanism 30 is moved to its closedposition thereby causing the movable rod 39 to move forwardly andrelease the movable contact so it closes with the fixed contact andcompletes a circuit therethrough. The second interlock switch is asingle pole, single throw lock switch 65 that is normally closed whenthe solenoid 54 is do energized as is shown in FIGURE 3. This switch isengaged and held closed by a collar 66 formed on the plunger 53 of thesolenoid when the solenoid is deenergized. Hence, when the solenoid 54is energized, the plunger 53 drops and the lock switch 65 isopencircuited. The eifect of these two interlock switches 63 and 65 willbest be understood during the explanation of the wiring diagram ofFIGURE 4 which follows.

The electric range of the present invention is provided with anelectrical service of three-wire Edison source of power; nominally of240 volts, single phase, 60 cycle, A.C. which is usually available inthe average resistance having adequate wiring. This voltage source has apair of line wires L1 and L2 with a voltage of 240 volts therebetweenand a grounded neutral conductor N with half voltage or 120 voltsmeasured across any line wire L1 and L2 with the neutral conductor N forsupplying the electrical load of the oven characterized by the threeheating elements; the baking element 16, the broiling element 17 and themullion or perimeter heater 18. The power supply circuit to the load isbroken by an oven selector switch 68 which serves to make and break thecircuit and set-up the various circuit combinations which are availableto the housewife for the normal cooking operations such as baking,broiling and time baking as well as for setting up the high temperatureheat cleaning cycle for automatically removing the food soil from thewalls of the oven liner.

There is also a low voltage temperature control circuit for an oventhermostat or responder 69 which is supplied power from a step-downtransformer 70 to furnish about 12 volts in a circuit that includes theresponder 69, a variable resistance temperature sensor 71, a biasingresistor 72 which is adapted to shift the control point of the sensorfrom the normal cooking temperature range to a high temperature heatcleaning range as will be explained hereinafter, and an output relay R-2having single throw, double pole switch contacts 73, 73, for completingthe circuit to the heating elements in the event heat is desired.

In addition to the power circuit and the low voltage temperature controlcircuit, there is a door latch control circuit that includes thefollowing elements, a solenoid 54 in cooperation with a lock switch 65,a latch switch 63 cooperating with the movable rod 39 of the doorlatching mechanism 30, and a sequence timer 75 having an electric motordriving a series of cams to operate three timer switches 76, 77 and 78.Moreover, there is a single pole, single throw clean switch 102 enclosedin the timer and which is manually operated by setting the timer dial tothe circuit connections for these various electrical components as willbe described in more detail hereinafter.

The oven selector switch 68 is provided with a plurality of switchcontacts that are each labelled with the particular operation that isinvolved when the contacts are closed. These contacts are identified aselements 80-88. For example, during a baking operation contacts 80, 83,and 86 are closed. During a broiling operation, contacts 81, 85 and 86are closed. During a time baking operation contacts 80, 83, 84 and 86are closed. Finally, during a heat cleaning operation contacts 80, 82,86, 87 and 88 are closed.

The baking circuit has the bake element 16 connected directly acrosslines L1 to L2 at 240 volts, while at the same time the broil element 17is connected across line L2 and Neutral N at half voltage. The circuitmay be traced from line L2 through oven switch contacts 86 and by leads90, 91 through thermostat contacts 73, leads 92 and 93 to bake element16, lead 94 through thermostat contacts 73, lead 95 to oven switchcontacts 83 to line L1. At the same time the broil unit is connected tolead 93 by lead 96 and to neutral N by lead 97 through oven switchcontacts 80.

The broiling circuit has the broil element 17 as the only heatingelement that is energized and it is connected across lines L1 and 1.2 at240 volts. The circuit is from line L2 through switch contacts 86 andleads 90, 91 through thermostat contacts 73, leads 92, 93 and 96 andthrough broil unit 17, and by lead 97 through oven switch contacts 81 toline L1.

The time baking circuit is the same as the baking circuit except thatoven timer contacts 98 are located between line L1 and oven switchcontacts 84 for controlling power to the transformer 70 so as to be ableto make and break the circuit the bake and broil elements 16 and 17 as afunction of the position of the cams of the oven timer as is wellunderstood by those skilled in this art. When the oven timer contacts 98are opened, the transformer 70 is de-energized thus opening thethermostat contacts 73, 73. During the heat cleaning operation all threeheating elements, the bake element 16, the broil element 17 and themullion heater 18 are connected in parallel across line L2 and neutralconductor N at 120 volts. One side of the mullion heater 18 is connectedto line L2 through oven switch contacts 86 and leads 90, 91, thermostatcontacts 73, leads 92 and 99, while the other side of the heater isconnected to neutral conductor N through lead 100.

Turning back to a consideration of the temperature control responder orthermostat 69, it is of the general type that is taught in the UnitedStates patent to Baker 2,962,575. Such devices have proved to be quitesatisfactory for use an oven thermostats for normal cooking operations.However, none of them have been commercially available at a reasonableprice to extend over a wide temperature range that would cover, inaddition to the normal cooking temperatures, the heat cleaningtemperatures rising between about 750 F. and 950 F. and still have thenecessary degree of accuracy throughout the entire range oftemperatures. An improvement has been made in this control system by thecooperation of a biasing resistor 72 that is shunted across thevariableresistance temperature sensor 71 when the heat cleaningtemperature range is desired. The sensor 71 is preferably a resistorhaving a high temperature coefiicient of resistance and it is locatedwithin the oven cavity 13 to detect the oven air temperature therein.This shunt resistor 72 functions to shift the control point of thecircuit by dropping the effective resistance of the sensor so as to beable to attain accurate results for the complete range of temperaturesfor the oven. This feature of the design is disclosed and claimed in therecently issued patent of Stanley B. Welch No. 3,122,626 which isassigned to the General Electric Company, the assignee of the presentinvention.

The responder 69 is a manually settable thermostatic device thatincludes a pulsing voltage regulating relay (not shown) in series withthe sensor 71 so that the sensor varies the effective output voltage ofthe relay in accordance with the sensed temperature within the ovencavity regardless of variations in the line voltage. The thermostatincludes a responder relay (not shown) that receives the effectiveoutput voltage of the voltage regulating relay and controls an outputrelay R2 that includes the double pole thermostat contacts 73, 73 whichwere mentioned previously as being the switching means for controllingthe heating elements of the oven.

Returning to the door latch control circuit, the sequence timer 75 isused only during the heat cleaning operation and this timer includes atimer motor, the three timer switches 76, 77 and 78 and a clean switch102. The timer switch 76 is a single pole double throw switch havingfixed contacts 103 and 104, while the switches 77 and 78 are singlepole, single throw switches. The sequence timer 75 has four periods ofoperation during a complete cycle; namely, Off, Wait, Clean and Cool. Inorder to begin the heat cleaning cycle, the oven selector switch 68 isset at the Clean position which will close contacts 80, 82, 86, 87 and88 thereby energizing the solenoid 54 across line L2 and neutral Nthrough oven switch contacts 87 and leads 105, 106, through timer switch76 to contact 103 and lead 107, through the solenoid 54, and by lead 108to lead 100 and back to neutral N. This pulls the plunger 53 of thesolenoid down thereby dropping the locking pin 60 of the automaticlocking means 38 out of the detent 56 making it possible for the handlelever 31 of the door latching mechanism 30 to be swung to its closedposition locking the oven door 15. The closing movement of the handlelever 31 causes the movable rod 39 to shift forwardly thereby allowingthe latch switch 63 to close as seen in FIG. 3.

Also, the clean switch 102 of the sequence timer 75 is set to close andthis energizes the timer motor thereby indexing the timer cam into aWait period of about ten minutes duration at which time the timer switch77 is open and the clean switch 102 is held closed. An indicator lamp isshunted across the sequence timer 75 by leads 111 and 112 so as to beenergized whenever the timer is operating thus informing the housewifewhen the Clean cycle has been initiated. During the ten minute Waitperiod, the oven door 15 may be unlatched and opened since the solenoid54 remains energized thereby overriding the automatic locking means 38.The cleaning cycle may be discontinued by either or both unlatching thedoor and turning the oven selector switch 68 to the Off position. Thelatch switch 63 would be opened thereby stopping the timer motor, butthe timer switch 77 will remain open and the clean switch 102 closed. Asa result of this, the clean switch 102 will not have to be actuated thenext time the clean cycle is started.

A ninety minute Clean period follows the ten minute Wait period. TheClean period is started by the closing of both the timer switch 78 andtimer switch 76 moving to its other position as being closed withcontact 104. The closing of timer switch 78 will energize thetransformer 70 across line L1 and neutral N by means of leads 114, 115,116 to one side of the transformer 70, and then by lead 117 to lead 100and back to neutral N. The energized transformer 70 will supply power tothe oven responder 69 which will cause the responder contact HL to closethereby energizing the output relay R2 of the responder. The respondercontact HL will open and close at some predetermined oven temperaturethat is set by the manual dial (not shown) of the responder positionedat a Clean position. The output relay R2 is connected across line L2 andneutral N by means of lead 119 from line L2 through the responder 69 andlead 120 to the relay R2 and lead 121 from the relay to lead 100 andthen back to neutral N. Notice that the opening of the timer switch 76with respect to contact 103 will de-energize the solenoid 54, hence,allowing the automatic locking means 38 to engage the door latchingmechanism 30 and prevent this mechanism from being moved.

Moreover, the plunger 53 of the solenoid will rise until it closes thelock switch 65 and this energizes a relay Rl in the temperature controlcircuit which controls three switches 123, 124 and 125. The relay Rlitself is energized in the following circuit from line L2 through ovenswitch contacts 87 and leads 105, lead 106 through timer switch 76closed with contact 104, and then through the lock switch 65, and bylead 127 back through oven switch contacts 88 and by lead 128 to oneside of the relay R-l, then by lead 129 through a bi-metal safety switch130 which is an over-temperature switch that open whenever the oven airtemperature reaches a maximum of about 1000 F. Then by lead 131 to lead100 and then back to neutral N. This relay R-l serves to connect themullion heater 18 in the cleaning circuit by closing switch 123. Thisconnects the mullion heater 18 in parallel with both the bake and broilelements 16 and 17 across line L2 and neutral. Moreover, this relay Rlwill set the responder 69 from the normal temperature range to the heatcleaning temperature range by means of movement of switches 124 and toconnect the biasing resistor 72 across the temperature sensor 71. Thiswill cause the oven responder contacts HL to open and close at a cleantemperature of approximately 880 F. which is pre-set at the factory andnot controllable by the housewife. The responder contacts H-L will cycleopen and closed thereby breaking and making a circuit to the outputrelay R2 which in turn will open and close contacts 73, 73 therebycontrolling the power delivered to the heating elements. Switch 125 is adoublepole switch that is shown in the position of FIG. 4 as beingclosed with contact 126 when the responder is set for normal cookingoperations. When closed with the other contact 132, the responder isprovided with the biasing resistor 72 for cleaning operations asmentioned heretofore. An oven pilot light 133 is connected in thecircuit across line L2 and neutral by means of leads 134 and 135 so asto cycle On and Off with the Opening and closing of the respondercontacts 73, during Baking or Cleaning. There is also an indicator lamp136 connected between line L2 and neutral N by means of oven switchcontacts 86 to be energized whenever the oven switch 68 is set to aheating position.

The heat cleaning cycle may be stopped at any time by merely turning offthe oven selector switch 68 thereby cutting the power to all of theheating elements. This does not cut the power to the sequence timer 75which will continue running. Thus, the door latching mechanism 30 willremain locked by the automatic locking means 38 since the solenoid 54remains tie-energized as long as the timer runs.

At the end of the Clean cycle, the sequence timer 75 will go into atwenty-minute Cool period. The cool period is started by the opening oftimer switch 76 into an intermediate position not making contact witheither of its contacts 103 or 104. This will de-energize the relay R-lthereby opening the relay switches 123 and 124 and closing switch 125with contact 126, which will cut out the mullion heater 18 as well asthe biasing resistor 72 thereby causing the oven responder 69 to be setback to its normal cooking temperature range. Moreover, this will cutoff the power to all of the heating elements in the same manner that theopening of the bimetal safety 130 accomplishes this result.

At the end of the Cool period, the clean switch 102 and the timer switch78 will open, and the timer switch 76 will close with contact 103 andtimer switch 77 will close. This switching will terminate the Cleancycle and will likewise energize the solenoid 54 thereby opening thelock switch 65 and dropping the lock pin 60 out of the detent 57 therebyenabling the manual operation of the door latching mechanism 30. Thetransformer 70 will be de-energized when the timer switch 78 is openedand this in turn will cut the power to the oven responder 69 and openthe responder contacts H-L thereby de-energizing the output relay R-2and open the responder contacts 73, 73 thereby cutting off the power tothe bake and broil elements 16 and 17, respectively. The opening of theclean switch 102 will stop the motor of the timer 75 and also shut offthe indicator lamp 110. This will denote to the housewife that the cleancycle is terminated so that the door may be unlatched and the ovenswitch 68 turned oh". The solenoid 54 will be de-energized when the ovenswitch 68 has been turned olf. This operation will automatically lockthe door latch mechanism 30 in the unlatched position with the lockingpin 60 located in detent 56.

The basic heat cleaning operation is controlled through the oven switch68 and by the solenoid 54, door latching mechanism 30, sequence timer 75and the relay R-l. These components are only used in the door latchcontrol circuit when the oven switch 68 is set to a Clean position. As aresult, the circuit may be used for the normal cooking operation ofBake, Broil and Time Bake without any interference from the door latchcontrol circuit.

Modifications of this invention will occur to those skilled in this artand therefore it is to be understood that this invention is not limitedto the particular embodiments disclosed, but that it is intended tocover all modifications which are within the true spirit and scope ofthis invention as claimed.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. A high temperature oven for domestic use comprising a cabinetstructure, an oven liner in said cabinet structure defining a [A] heatedcooking cavity, and an access door for closing said cavity, electricalheating means connected to a source of electrical energy for raising thetemperature within the cavity for normal cooking operations betweenabout F. and 550 F. as well as for a heat cleaning operation thatreaches above 750 F. for removing food soil lodged on the walls of theoven liner, and door latching means movable between open and closedpositions and adapted to hold the door in a closed position during saidheat cleaning operation [a high temperature cycle], locking means forlocking the door latching means in its closed position at temperaturesabove the normal cooking temperatures, and electro-responsive means forreleasing the locking means, and control circuit means connected to saidelectroresponsive means for energizing the electroresponsive means, andmeans to de-activate the control circuit means during the heat cleaningoperation [high temperature cycle] at temperatures above normal cookingtemperatures so that the door latching means may not be unlocked and thedoor opened during such cycle, said ale-activating means comprising anon-electromagnetic switch connected direclly in said circuit means.

2. A high temperature oven for domestic use comprising a cabinetstructure enclosing a box-like oven liner that has an open frontprovided with an access door that cooperates with the oven liner todefine an oven cooking cavity, heating means for supplying heat energyinto the oven cavity for normal cooking operations between about 150 F.and 550 F. as well as for a heat cleaning operation between about 750 F.and 950 F. for removing food soil lodged on the walls of the oven liner,and door latching means movable between open and closed positions forholding the door closed during the heat cleaning operation, and aspring-actuated locking means automatically engageable with the doorlatching means when the door latching means is in its closed position,and an electroresponsive means connected with the said locking means,circuit control means for the electroresponsive means so that when theelectroresponsive means is energized it disables the locking means andpermits [permit] the free movement of the door latching means, and timermeans for controlling the length of the heat cleaning cycle, and meansto de-activate the circuit control means during the heat cleaning cycleat temperatures above normal cooking temperatures so that the doorlatching means may not be unlocked and the door opened until the oventemperature returns to within the normal cooking temperature range.

3. A self-cleaning oven for domestic use having a heated cavity formedby an insulated box-like body and an access door for closing saidcavity, heating element means for converting an energy source into heat,and a selector switch means governing the supply of power to the heatingelement means for normal cooking operations between about 150 F. andabout 550 F. as well as for a heat cleaning operation between about 750and about 950 F. for removing food soil lodged on the walls of the ovencavity, and door latching means movable between open and closedpositions and adapted to hold the door closed during the heat cleaningoperations; the invention comprising means for locking the door latchingmeans in the closed position during the heat cleaning operation so thatthe oven door may not be opened at temperatures above normal cookingtemperatures, [and] an electroresponsive means for releasing} thelocking means at the completion of the heat cleaning operation so thatthe oven door may be opened, and control circuit means for energizingsaid electrorespom sive means, said control circuit means including asingle non-electromagnetic switch connected directly therein formaintaining said electroresponsive means a e-energized during the heatcleaning operation so that said door may not be opened during saidoperation.

4. In a domestic oven comprising an insulated cabinet supplied with anoven liner and an access door to form an oven cooking cavity, electricalheating means for said oven cavity, a circuit network adapted to connectthe heating elements to an electrical power supply, switching means forthe circuit network to elTect baking, broiling and heat cleaningoperations, the baking and broiling operations having normal cookingtemperatures between about 150 F. and about 550 F., While the heatcleaning operation is carried out at temperatures between about 750 F.and about 950 F. for removing food soils lodged on the walls of the ovencavity, and door latching means movable between Open and closedpositions for holding the door closed during the heat cleaningoperation; the invention comprising spring-actuated locking means forlocking the door latching means in its closed position, interlock switchmeans in the circuit network of the heat cleaning operation that isclosed when the door latching means reaches the closed position, releasemeans for the locking means, and means for deactivating the releasemeans whenever the door latching means is in a closed position and heldclosed by the locking means and the oven temperature is above the normalmaximum cooking temperature of about 550 F., whereby the oven door islatched closed and may not be opened while the oven temperature is abovenormal cooking temperatures.

5. In a domestic oven as recited in claim 4 with the addition of asecond interlock switch means in the circuit network of the heatcleaning operation that is closed when the locking means is in itslocked position before the heat cleaning operation can be initiated.

6. In a domestic oven as recited in claim 4 wherein the door latchingmeans includes a movable rod extending to the back of the oven liner andis provided adjacent its end with a pair of spaced keeper portionsrepresenting the open and closed positions of the door latching means,the locking means being biased into one of the keeper portions dependingupon the position of the door latching means.

7. in a domestic oven as recited in claim 6 with the addition of asecond interlock switch means in the circuit network of the heatcleaning operation that is closed when the locking means is in itslocked position while the door latching means is also in its lockedposition before the heat cleaning operation can be initiated.

8. A cooking apparatus comprising walls defining an oven cavity, onewall of the cavity including a door for gaining access thereto, heatingmeans supplied for the ovenv and cleaning means operable for theautomatic cleaning of the inner walls of the cavity by causing theheating means to raise the temperature of the cavity to a maximumtemperature in the range of about 750 F. to about 950 F. and therebydegrade food soil adhering to the cavity walls, means controlling saidheating means to heat said cavity to within said temperature range; theinvention comprising door latching means for sealing the door of theoven cavity at temperatures above about 550 F., the door latching meansbeing movable between open and closed positions, a movable rod connectedto the door latching means, the rod extending to the back of the apparatus and away from the door, an automatic locking means coopcrablewith the rear end of the said rod for locking the door latching means inthe closed position, the said control means including both an interlockswitch means that is closed when the door latching means reaches theclosed position, and a second interlock switch means that is closed whenthe automatic locking means is in its locked position thereby insuringthat the door is held closed by the door latching means and the doorlatching means is held closed by the automatic locking means before theautomatic cleaning cycle can be initiated, and release means forovercoming the automatic locking means so as to allow the manualoperation of the door latching means, and sequence timer means tocontrol the length of the cleaning cycle and to cause the operationoithe release means only after the completion of the cleaning cycle whenthe temperature has returned to with- 12 in the normal cookingtemperature range of about 550 F. and below.

9. A cooking apparatus as recited in claim 8 wherein the automaticlocking means, the two interlock switch means and the release means areall located at the back of the apparatus away from the oven door so asto be in a relatively cool area, the said automatic locking means beinga spring-biased member that is cngageable with a portion of the movablerod, the said release means being an electroresponsive means that isconnected to the said spring-biased member for overcoming the action ofthe spring in order to be able to unlock the door.

10. The heated cavity as recited in claim 1 wherein the said lockingmeans include spring-actuated means.

11. The heated cavity as recited in claim 10 wherein the said means tode-activate the control means during high-temperature cycle includetime-responsive means.

12. The self-cleaning oven as recited in claim 3 wherein the means forlocking the door latching means include spring-actuated means.

13. A high temperature oven for domestic use comprising a cabinetstructure enclosing a box-like oven liner that has an open frontprovided with an access door that cooperates with the oven liner todefine an oven cooking cavity, heating means for supplying heat energyinto the oven cavity for normal cooking operations between about F. andabout 550 F. as well as for a heat cleaning operation between about 750F. and about 950 F. for removing food soil lodged on the walls of theoven liner, and door latching means movable between open and closedpositions for holding the door closed during the heat cleaningoperation, and locking means for locking the door latching means whenthe door latching means is in its closed position, and electroresponsviemeans for releasing the said locking means, circuit control means forthe electroresponsive means so that when the electroresponsive means isenergized at temperatures within normal cooking temperatures it releasesthe locking means, and means to de-activate the circuit control meansduring the heat cleaning operation at temperatures above normal cookingtemperatures so that the door latching means may not be unlocked and thedoor opened during said operation.

14. The oven as recited in claim 13 with the addition of timer means forcontrolling the length of the heat cleaning operation, and wherein thesaid locking means include spring-actuated means.

15. The oven as recited in claim 14 wherein the said means to deactivatethe control circuit means during the heat cleaning operation includetime-responsive means.

16. In a domestic oven comprising an insulated cabinet supplied with anoven liner and an access door to form an oven cooking cavity, electricalheating means for said oven cavity, a circuit network adapted to connectthe heating elements to an electrical power supply, switching means forthe circuit network to effect baking, broiling and heat cleaningoperations, the baking and broiling operations having normal cookingtemperatures between about 150 F. and about 550 F., while the heatcleaning operation is carried out at temperatures between about 750 F.and about 950 F. for removing food soils lodged on the walls of the ovencavity, and door latching means movable between open and closedpositions for holding the door closed during the heat cleaningoperation; the invention comprising spring-actuated locking means forlocking the door latching means in its closed position, interlock switchmeans in the circuit network of the heat cleaning operation that isclosed when the locking means reaches the latch-locking position,release means for the locking means, and means for de-activating therelease means whenever the door latching means is in a closed positionand held closed by the locking means and the oven temperature is abovethe normal maximum cooking temperature of about 550 F, whereby the ovendoor is latched closed and may not be opened While the oven temperatureis above normal cooking temperatures.

17. A high temperature oven for domestic use comprising a cabinetstructure enclosing a box-like oven liner that has an open frontprovided with an access door that cooperates with the oven liner todefine an oven cooking cavity, heating means for supplying heat energyinto the oven cavity for normal cooking operations between about 150 F.and about 550 F. as well as for a heat cleaning operation between about750 F. and about 950 F. for removing food soil lodged on the walls ofthe oven liner, and door latching means movable between open and closedpositions for holding the door closed during said heat cleaningoperation, and locking means for locking the door latching means whenthe door latching means is in its closed position, and eleetroresponsivemeans for releasing the said locking means, circuit control means forthe electroresponsive means so that when the electroresponsive means isenergized it releases the locking means, and means to a e-activate thecircuit control means during the heat cleaning operation at temperatureabove normal cooking temperature so that the door latching 14 means maynot be unlocked and the door opened during the upper part of saidoperation, said last mentioned means comprising a timer switch connecteddirectly in said circuit control means.

References Cited The following references, cited by the Examiner, are ofrecord in the patented file of this patent or the original patent.

UNITED STATES PATENTS 2,470,043 5/1949 Monsarrat 3445 3,113,200 12/1963Hurko 2174()9 3,121,158 2/1964 Hul'ko 2l9-397 3,214,567 10/1965 Chisholm219-4l4 3,317,708 5/1967 Bowling 219412 3,301,999 1/1967 Chrisholm219393 VOLODYMYR Y. MAYEWSKY, Primary Examiner US. Cl. X.R.

